One of the conventionally known semiconductor laser apparatus is a semiconductor laser apparatus comprising a semiconductor laser array having a plurality of active layers arrayed in parallel along a predetermined direction, a collimator lens for collimating a plurality of beams emitted from the plurality of active layers, in a direction perpendicular to the array direction of the active layers, and a path changing element for receiving the beams collimated by the collimator and for rotating the transverse sections of the beams by about 90° (e.g., cf. Document 1: Japanese Patent No. 3071360).
FIGS. 1A and 1B are views for explaining the divergence angle of a beam emitted from each active layer 103 of the semiconductor laser array 101 in the semiconductor laser apparatus described in this Document 1. FIG. 1A is a side view showing the divergence angle of the beam and FIG. 1B a plan view showing the divergence angle of the beam. The coordinate axes (x-axis, y-axis, and z-axis) are set as follows: the direction of the x-axis is defined along a direction of emission of laser light from the semiconductor laser array, the direction of the y-axis along the array direction of the active layers, and the direction of the z-axis along the direction perpendicular to both the x-axis direction and the y-axis direction. The divergence angle in the z-axis direction of the beam emitted from each active layer is 30°-40° with a center on the optical axis 105 (FIG. 1A), and the divergence angle in the y-axis direction 8-10° (FIG. 1B). The semiconductor laser apparatus described in the foregoing Document 1 is constructed in a structure in which the collimator lens collimates the beams in the vertical direction and thereafter the path changing element rotates the sections of the beams by 90°, so as to keep the adjacent beams less likely to intersect with each other.